Pengolahan Limbah Cair Tahu Menjadi Biogas Menggunakan Reaktor Biogas Portabel

From the tofu production process. The waste generated by tofu industries can be divided into two types, i.e the solid waste and liquid waste. One effort to reduce the environmental damage due to tofu liquid waste from the processing of tofu is to make the tofu liquid waste into biogas. The effort to convert liquid waste from tofu factories into biogas reguires a biogas reactor.  The aim of this study was to design a biogas reactor with a size of 1 m3 (1000 Liters) by using materials and equipment that are very easily available in the market at an affordable price, to determine the pressure, pH value and the quality of the flame produced when the biogas is used as fuel gas stove. The method used in this study is an experimental method within 30 days. The results showed that biogas pressure increased with increasing time (days). Maximum pressure is reached on day 21, which is 12.2 kPa. The average pH value is 6.91. The temperature in the biogas reactor tends to be stable with an average temperature of 31oC. The color of the flame when the biogas from tofu liquid waste is used as a gas fuel for a large flame gas stove is still a mixture of blue and yellow. The utilization of tofu liquid waste into biogas is expected to reduce environmental pollution and make tofu liquid waste become a high economic value and environmentally friendly

Effect of Pattern Coating Thickness on Surface Roughness and Porosity of Nodular Cast Iron (FCD) 450 Using Lost Foam Casting Method

Lost foam casting is one of casting method that usesexpanded polystyrene (EPS) foam as a mold pattern andembedded into silica sand. When the molten metal is poured intoa mold, EPS will melt and evaporate, so the cavity is filled by themolten metal. The main objective of this research was toinvestigate the effect of pattern coating thickness on surfaceroughness and porosity of nodular cast iron FCD 450 by using thelost foam casting method. The mold pattern of EPS foam has 17kg/m3 of density and 3-24 mm of section thickness. Coatingmaterial was used a refractory material of Zircon (ZrO2) andbinder of Colloidal Silica (O2Si). In order to study effects of coatingthickness, experiments were conducted with of 0-1300 μm. FCD450 metal alloy was melted in a crucible furnace and the moltenmetal was poured into a mold at temperatures of 1350 °C-1450 °C.The experimental results showed the surface roughness decreaseswith increasing coating thickness of the EPS pattern. Uncoated ofEPS pattern influenced the casting quality. The porosity increaseswith coating thickness of EPS pattern

Analisis Sifat Mekanik dari Struktur Seluler yang Difabrikasi dengan Printer 3D

Struktur ringan berbentuk cellular (seluler) atau foam (busa) dalam beberapa tahun terakhir sangat banyak dikembangkan terutama karena perkembangan cepat dari Printer 3D, sehingga desain rumit dapat difabrikasi dengan mudah. Struktur seluler mempunyai rasio kekuatan terhadap massa dan kekakuan yang tinggi, serta dapat diaplikasikan pada struktur ringan dengan ketahanan impak yang tinggi. Dalam tulisan ini, dilakukan uji tekan terhadap enam jenis struktur seluler dengan fraksi volume 10%. Jenis struktur seluler yang divariasikan adalah Cubic, Gyroid, Honeycomb 3D, Rectilinear, Honeycomb, dan Rectilinear 45o. Hasil yang didapat menunjukkan bahwa struktur kompleks jenis Cubic mempunyai kekuatan maksimal terbaik dan juga mempunyai penyerapan energi yang terbaik berdasarkan pengujian yang dilakukan, diikuti dengan struktur Gyroid dan Honeycomb 3D. Struktur yang mempunyai topologi dua dimensi yaitu, Rectilinear 0o, Rectilinear 45o, dan Honeycomb tidak mempunyai kekuatan dan karakteristik penyerapan energi yang baik. Hasil ini dapat digunakan sebagai panduan desain struktur ringan yang mempunyai karakteristik kekuatan dan penyerapan energi mekanik yang tinggi

Recycling of Magnesium Alloy Scrap by Remelting and Chemical De-coating Process

The growing demands of magnesium (Mg) based materials had risen new challenges related to disposal of unused parts and a huge amount of waste made by such metals. Attempts to recycle the scrap of these materials through remelting had become one of the preferred choices. However, a series of preliminary steps should be carried out to reduce the impurities as well as to maintain the quality of the casted ingot, for instance, by applying de-coating for removing paints or coating substrates at the scrap surface prior to remelting. In this research, the effects of chemical reagent de-coating on the properties of ingot obtained from recycling Mg scrap were studied. A commercial paint removal liquid was preferred as the reagent for removing paint layers over the Mg scrap surface. The de-coated scrap was then remelted in a conventional furnace with NaCl powder as the fluxing layer. The results of this study noticed the importance of chemical de-coating process to reduce the impurity contents in the ingot which might be originated from the coating or paint substrates covering the Mg scrap. Meanwhile, the density and hardness of the Mg ingot processed without de-coating were obviously higher than that had been cleaned previously with paint removing agent

DESIGN OF BIOGAS PURIFICATION TO REDUCE CARBON DIOXIDE (CO2) AND HYDROGEN SULFIDE (H2S)

Biogas is a gas produced from decomposition of organic matter by microorganisms in anaerobic conditions. The problems that are mainly from the development of biogas technology are the high levels of H2S and CO2 in biogas which become an obstacle in the application of biogas directly because it can lead to corrosive components of energy conversion equipment (generator sets) and can reduce the heating value in biogas combustion. The aim of the paper is to design a biogas purification device using Calcium Hydroxide Ca(OH)2, Iron Oxide (Fe2O3), Zeolite, and Activated Carbon in the biogas which are designed according to the characteristics of the biogas installation in Indonesia. From experimental results the percentage of methane gas content increased from 52.5% to 90.2% after purification. Ca(OH)2 solution can be used for adsorbent to increase methane gas levels and reduce CO2 levels in biogas. Fe2O3 iron powder can be used to reduce the levels of H2S content in biogas so that it can increase methane gas content and is safe to use on generator engines.Zeolite and Activated Carbon can increase methane gas levels and reduce the moisture content and CO2 contained in the biogas so that when the biogas is applied to the generator engine. The power generated in the generator engine using biogas fuel that has been purified is greater than that which has not been purifie

PENGARUH KETEBALAN LAPISAN POLA PADA METODE LOST FOAM CASTING TERHADAP AKURASI UKURAN BESI COR NODULAR FCD 450

Abstrak Lost foam casting merupakan salah satu metode pengecoran yang menggunakan bahan expanded polystyrene (EPS) sebagai bahan untuk pembuatan pola dan ditanam dalam pasir silika. Ketika logam cair dimasukkan ke dalam cetakan, EPS akan mencair dan menguap sehingga tempat itu akan diisi oleh cairan logam. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh tebal lapisan pada pola expanded polystyrene terhadap akurasi ukuran besi cor nodular FCD 450 dengan menggunakan metode lost foam casting. Pola EPS yang digunakan memiliki ketebalan 3-24 mm. Material pelapis yang digunakan adalah material rekraktori Zircon (ZrO2) dan bahan pengikat Colloidal Silica (O2Si). Ketebalan material pelapis yang diterapkan pada pola EPS yakni 0-1300 mikron. Pola EPS ditanam dalam pasir silika kemudian dipadatkan dengan cara digetarkan. Paduan logam FCD 450 dilebur dalam crucible furnace dan dituang ke dalam cetakan pada suhu sekitar 1350 oC-1450 oC. Rata-rata akurasi ukuran untuk masing tebal lapisan pola 0 (tanpa pelapisan), 200, 500 dan 1300 mikron berturut-turut adalah -0,05, 0,04, -0,07, dan -0,13. Tebal lapisan 200 mikron memberikan nilai akurasi ukuran terbaik dari ketiga variasi ketebalan lapisan pola. Tebal lapisan 0 (tanpa pelapisan), 500 dan 1300 mikron akan mengakibatkan penurunan akurasi ukuran. Pola yang tidak dilapisi akan memberikan dampak yang buruk terhadap hasil coran.   Kata kunci: akurasi ukuran, besi cor nodular FCD 450, expanded polystyrene (EPS), lost foam castin

Analisa Pengaruh Variasi Media Pendingin Pada Perlakuan Panas Terhadap Struktur Mikro Dan Nilai Kekerasan Fully Pearlitic Steel

Penelitian ini bertujuan untuk mengetahui pengaruh variasi media pendingin pada perlakuan panas terhadap nilai kekerasan dan struktur mikro fully pearlitic stell. Proses penelitian dilakukan dengan pemotongan fully pearlitic stell dengan ukuran 10 x 10 x 10 mm, kemudian dilakukan proses perlakuan panas dengan temperatur 900℃, selanjutnya dilakukan proses pendinginan dengan berbeda media pendingin seperti: udara, di dalam oven, air, oli bekas, dan salah satu spesimen yang tidak dilakukan perlakuan apapun sebagai pembanding. Hasil pengujian struktur mikro rel tanpa perlakuan mengandung struktur perlit dan ferit, dengan nilai kekerasan yang didapat 392,64 HVN. Media pendingin udara memiliki fasa ferit dan perlit, dengan nilai kekerasan 335,92 HVN. Pendinginan di dalam oven struktur mikronya adalah sementit, perlit, austenit dengan nilai kekerasan yang diperoleh 287,67 HVN, merupakan nilai kekerasan terendah. Untuk media pendingin air struktur mikro yang terbentuk ferit, austenit, martensit, nilai kekerasannya 915,89 HVN. Untuk pendinginan oli bekas struktur mikronya martensit, austenit, ferit dengan nilai kekerasan 916,38 HVN, media pendingin oli bekas mendapatkan nilai kekekarasan tertinggi.Kata kunci: Perlakuan panas, baja karbon tinggi, kekerasan, struktur mikro